The present invention relates to a flexibility adjustment fastener, particularly for ski boots.
The problem of being able to adjust the angular position of the quarters with respect to the plane of the sole is currently strongly felt: in known ski boots, this variation is obtained for example by imparting a deformation to the quarters, with consequent problems due to fatigue of the materials or to permanent deformations.
In known central- or rear-entry ski boots, which as such have a shell with overlapping flaps and with separate front and rear quarters, there is the problem due to the fact that the transverse translatory motion of the front quarter, in direct contact with the shell, for the adjustment of the angular position with respect to the sole, creates empty spaces in the region at which the two components overlap one another.
This situation causes a variation in the interference characteristics and therefore in the flexibility of the boot.
It has furthermore been observed that during flexing, since the quarters are mutually secured and articulated at the same point on the shell, their degree of mutual securing is altered.
As a partial solution to these disadvantages, this same Assignee filed Jul. 9, 1982, U.S. patent application Ser. No. 06/396,548 granted Mar. 18, 1986 as U.S. Pat. No. 4,575,955.
In said Patent, which is incorporated herein by reference, said boot has the peculiarity of having a front quarter which has a first part which predominantly affects the lateral regions of a skier's leg and is pivoted to the shell, and a second part which predominantly affects the front region of the skier's leg; said second part can be partially superimposed on the first part and is articulated thereto so as to allow a different degree of inclination with respect to the shell in the direction of the tip thereof.
Though this solution is undoubtedly valid, it has the disadvantage of maintaining a considerable lateral rigidity for the quarter, since the first and second parts are mutually fixed and are therefore subjected to deformations, especially if said boot is used in connection with a "snowboard".
This same Assignee filed Jul. 16, 1984, U.S. patent application Ser. No. 06/631,361 granted Sep. 16, 1986 as U.S. Pat. No. 4,611,415, which discloses a flexibility adjustment device in ski boots and the like, the peculiarity of which consists of the fact that it comprises at least one elastic element supported by the shell, an articulation pivot passing through said elastic element, at least the front quarter being connected to said pivot.
This solution still has limitations: the elastic element in fact only allows to damp the oscillation of the quarters exclusively along their longitudinal axis: this is still a limitation if the boot is of the type which can be used for snowboarding.